(Topic ID: 40037)

Doctor Who mini playfield shorting issue

By cyclejones

9 years ago



Topic Stats

  • 8 posts
  • 7 Pinsiders participating
  • Latest reply 8 years ago by rgb635
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#1 9 years ago

Hey everyone, I'm hoping someone can help me out and that this is a short within the mini-playfield and not a larger board issue...

For people who have a Doctor Who machine, you know the sequence that happens when the time expander isn't lit and you get a ball into one of the locks? how it makes that spacey-wacey sound and then pops the ball back out of the lock?

my machine is doing that any time mini playfield gets hit by the ball, and if the ball does go into the lock even when the time expander should be lit, it still kicks it back out at me. sometimes it even does it on it's own without being hit. I've also had a few times where after I go into the menu and run mini-playfield tests (which all show no errors), once I get the glass back on and hit start, the playfield which usually goes up and down once after a restart, will go up and down repeatedly over and over until I open the coin door and open the menu.

any thoughts? I really hope it's not something in the board, but this is something I haven't seen before.

#2 9 years ago

I'd go through the wiring harness first, to see if any obvious breaks or shorts, anything loose enough so pushing or pulling triggers something.

LTG : )

#3 9 years ago

Check your switches in switch test and make sure all are working correctly. Also check setting A2-47 and make sure the mini-playfield is not disabled.

#4 9 years ago
Quoted from kguenther6:

Check your switches in switch test and make sure all are working correctly. Also check setting A2-47 and make sure the mini-playfield is not disabled.

Yep. Very good advice.

#5 9 years ago

Would it still go up and down at all if it were disabled?

Another thing to check if switch test doesn't give you any useful information....

There are seven different connections (Wiring harnesses) for the MPF. As anyone who's had to take it out for adjusting is too familiar with lol. Run them all through a multimeter....you can test the ones cabinet-side by having the MPF out and then running through the tests for it seperately. You'll get a ton of errors because it thinks it's moving it up and down when it isn't, but what you want to check is that each thing is putting out (or cutting off) the same amount each time it runs through that test.

Be careful where you put fingers and metal things when you have it plugged in.

1 month later
#6 9 years ago

Normally the MPF does not work when it is disabled OR when your machine encounters an error in one of the optical switches (behind the white buttons). Mine had the same problem and I found out two of the optical switches where always triggered. It turned out that the receptors did not work on two buttons. I fixed it and the MPF worked like a charm (for two weeks, then a ball got stuck when the MPF was lowering and now it only rises an inch...)

1 month later
#7 8 years ago

Update: So after taking out the MPF and cleaning all of the sensors/contacts, the problem persisted. A switch test revealed switch 77 (right opto) was open (should be closed). I ordered a new set of opto's and replaced them. there was a crack and quite a bit of yellowing on the transmit LED that i replaced. put the whole thing back together. The problem still persists. A multimeter test of the IR receiver switch (its the only part I can reach with probes when the machine is assembled shows that the correct voltage is going to the wires, and if it bypass the switch by contacting the leads with a piece of wire, the test chimes and shows closed but only for a moment with each contact. I cannot get it to remain closed with continued contact. Any ideas?

#8 8 years ago

I had some simular problems to this and it turned out to be a bad opto board. The time expander would never lock two balls as it was suposed to and at times it would cycle up / down on its own. The problem turned out to be a bad opto board even though the opto switch test were unremarkable. I replaced it with a board from GLM http://www.greatlakesmodular.com/ and all was well.

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